1. Field of the Invention
This invention relates to an electrophotographic photosensitive member, a process for producing it, and a process cartridge and an electrophotographic apparatus which have the electrophotographic photosensitive member. More particularly, the present invention relates to an electrophotographic photosensitive member having a surface layer containing a specific resin, a process for producing it, and a process cartridge and an electrophotographic apparatus which have such an electrophotographic photosensitive member.
2. Related Background Art
In recent years, as materials used in electrophotographic photosensitive members, organic photoconductive materials are put into wide use because of their advantages such that they are causative of no environmental pollution and have a high productivity. In order to satisfy both electrical properties and mechanical properties, such electrophotographic photosensitive members are often utilized as photosensitive members of a function-separated type having a charge generation layer and a charge transport layer which are formed superposingly.
Meanwhile, as a matter of course, electrophotographic photosensitive members are required to have sensitivities, electric properties and also optical characteristics in accordance with electrophotographic processes applied.
In particular, to surface layers of photosensitive members used repeatedly, electrical and mechanical external force such as charging, exposure, development by toner, transfer to paper and cleaning is applied, and hence the surface layers are required to have durability to these. Stated specifically, they are required to have a durability to decrease in sensitivity, decrease in charging performance and increase in residual potential, and also to surface wear and scratching. In addition, the surface layers are required to have good properties in respect of transfer of toner images and cleaning for removing residual toner, and are required to have a small surface energy and a high lubricity for that purpose. Also, these performances are desired not to lower during repeated service.
It has been difficult for electrophotographic photosensitive members making use of organic photoconductive materials, to satisfy the above performances, in particular, the durability (or running performance).
Surface layers of the electrophotographic photosensitive members making use of organic photoconductive materials are commonly thin resin layers, where the properties of resin are very important. As resins that can satisfy the above various performances to a certain extent, acrylic resins and polycarbonate resins are recently put into practical use. However, it does not follow that these resins can satisfy all the performances stated above. In particular, it is hard to say that these resins have a sufficiently high hardness for achieving a much higher running performance. Even when these resins are used as resins for surface layers, the surface layers may wear or have scratches with repeated service. Also, from a demand for higher sensitivity in recent years, low-molecular weight components such as charge-generating materials are often added in a relatively large quantity, so that the low-molecular weight components may become deposited during the storage of electrophotographic photosensitive members. In addition, adhesion of machine oil and resin may cause cracks (solvent cracks).
As a means for solving these problems, use of a curable resin as a resin for the charge transport layer is disclosed in, e.g., Japanese Patent Application Laid-open No. 2-127652. The use of a curable resin as a resin for the charge transport layer to make the charge transport layer cure to effect cross-linking makes its strength higher to bring about an improvement in wear resistance, scratch resistance, deposition resistance and solvent crack resistance against repeated service.
However, the charge transport performance of such a layer containing a organic photoconductive material such as the charge-transporting material and also containing the curable resin depends greatly on the resin. Also, a layer having a sufficiently high hardness tends to decrease in charge transport performance, and tends to increase in residual potential during repeated service. Thus, with a demand for much higher image quality and higher running performance in recent years, it is studied how both the hardness and the charge transport performance can be achieved at a higher level.
An object of the present invention is to solve the problems the electrophotographic photosensitive members making use of conventional resins as surface layers have had, to thereby provide an electrophotographic photosensitive member that has been improved in wear resistance and scratch resistance by making film hardness higher and also has a good deposition resistance and solvent crack resistance.
Another object of the present invention to provide an electrophotographic photosensitive member that may very less cause changes or deterioration of performances, e.g., an increase in residual potential, and can exhibit a stable performance even during repeated service.
Still another object of the present invention to provide a process for producing the above electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus which have the photosensitive member and can maintain a high image quality for a long term.
The present invention provides an electrophotographic photosensitive member comprising a support and a photosensitive layer formed thereon;
which electrophotographic photosensitive member has a surface layer containing a charge-transporting material and a resin obtained by irradiating (i.e., exposing to radiations) a compound having an acryloyloxy group or methacryloyloxy group to cure.
The present invention also provides a process for producing an electrophotographic photosensitive member which has a support and a photosensitive layer formed thereon, the process comprising the step of;
forming a surface layer of the electrophotographic photosensitive member; the surface layer containing a charge-transporting material;
the step comprising the step of irradiating (i.e., exposing to radiations) a solution containing a compound having an acryloyloxy group or methacryloyloxy group, to cure the compound.
The present invention still also provides a process cartridge and an electrophotographic apparatus which have the electrophotographic photosensitive member described above.